Table 1.
Characteristics of the study population by sex or age
| Characteristics | Values* | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Boys (n 6750) | Girls (n 5676) | |||||||||||||
| Total (N 12 426) | 7–10 years | 11–14 years | 15–17 years | 7–10 years | 11–14 years | 15–17 years | ||||||||
| Mean or ratio | sd or % | Mean or ratio | sd or % | Mean or ratio | sd or % | Mean or ratio | sd or % | Mean or ratio | sd or % | Mean or ratio | sd or % | Mean or ratio | sd or % | |
| Height (cm) | 142·5 | 14·5 | 135·2 | 8·5 | 157·3 | 10·3 | 173·6 | 6·4 | 134·4 | 9·2 | 154·8 | 7·4 | 161·8 | 5·8 |
| Weight (kg) | 38·1 | 14·1 | 33·1 | 9·2 | 49·8 | 13·6 | 69·0 | 16·1 | 30·4 | 8·2 | 46·3 | 11·0 | 55·5 | 10·3 |
| BMI (kg/m2) | 18·2 | 3·7 | 17·9 | 3·3 | 19·9 | 4·0 | 22·8 | 4·8 | 16·6 | 2·8 | 19·1 | 3·6 | 21·1 | 3·5 |
| BF% (%) | 19·1 | 9·5 | 18·4 | 10·6 | 18·4 | 11·1 | 16·8 | 8·5 | 18·0 | 7·1 | 23·2 | 8·3 | 27·7 | 6·2 |
| Fat mass (kg) | 8·1 | 6·8 | 6·9 | 5·9 | 10·3 | 8·8 | 12·8 | 9·7 | 6·0 | 4·3 | 11·6 | 6·9 | 16·0 | 6·7 |
| Fat-free mass (kg) | 30·0 | 9·2 | 26·2 | 4·4 | 39·5 | 7·3 | 56·2 | 7·6 | 24·4 | 4·9 | 34·7 | 5·1 | 39·5 | 4·9 |
| Total body water (kg) | 22·0 | 6·8 | 19·2 | 3·2 | 28·9 | 5·4 | 41·1 | 5·6 | 17·9 | 3·6 | 25·5 | 3·8 | 29·2 | 3·6 |
| Adiposity rate† (%) | 18·5 | 17·9–19·2 | 25·7 | 24·4–27·0 | 26·5 | 24·4–28·5 | 15·7 | 12·2–19·2 | 6·9‡ | 6·1–7·7 | 20·1 | 18·0–22·2 | 11·3‡ | 8·1–14·5 |
| Obesity rate by BMI-based cut-offs (%) | ||||||||||||||
| IOTF | 15·2§ | 14·6–15·8 | 20·5§ | 19·3–21·7 | 18·0§ | 16·2–19·8 | 20·9§ | 17·0–24·8 | 9·6§ | 8·7–10·6 | 10·0§ | 8·5–11·6 | 8·7§ | 5·9–11·5 |
| WHO | 12·8§ | 12·2–13·4 | 20·4§ | 19·2–21·6 | 15·0§ | 13·4–16·7 | 11·6§ | 8·6–14·7 | 6·7 | 5·9–7·5 | 5·2§ | 4·0–6·4 | 3·7§ | 1·8–5·6 |
| WGOC | 13·5§ | 12·9–14·1 | 18·7§ | 17·6–19·9 | 13·4§ | 11·8–15·0 | 15·0 | 11·6–18·4 | 9·6§ | 8·7–10·5 | 8·3§ | 6·9–9·7 | 7·6§ | 5·0–10·3 |
BF%, body fat percentage; IOTF, International Obesity Task Force; WGOC, Working Group of Obesity in China.
*
Presented as mean and sd or ratio and 95 % CI.
†
Calculated by BF% cut-offs.
‡
Significant difference from girls aged 11–14 years, P < 0·01 (χ 2 test).
§
Significantly different from BF% cut-offs in the same sex and age group, P < 0·01 (McNemar’s test).